1. Field of the Invention
This invention relates to a method of stabilizing clayey geological formations by treatment with a quaternized oligomer.
2. Description of the Prior Art
When geological formations containing water swelling clays come in contact with water, particularly fresh water, clays in the formations may swell and/or disperse with attendant loss of permeability and/or mechanical strength to interfere with recovery of petroleum or other minerals from the formations. Clayey formations are often impermeable or have low permeability or lose part or all of their permeability on contact of the clays with water or water base systems such as injection fluids, drilling muds, stimulation fluids and gels.
Clays in formations can reduce permeability by swelling or migrating to form bridges or blockages in formation pores or screens used in well completions. Swelling and migrating occur when aqueous fluids used in oil recovery come in contact with the clays. High swelling clays used in drilling fluids may also invade a permeable producing formation during drilling to create low permeability zone in the vicinity of the borehole.
U.S. Pat. No. 3,349,032--Krieg, issued Oct. 24, 1967, describes a process for preventing, inhibiting or reducing "clay blocking" or plugging of oil producing clayey formations during oil recovery by adding a polyquaternary amine.
U.S. Pat. No. 3,500,925--Beiswanger et al, issued Mar. 17, 1970, describes a process for improving flow rate of injection water through oil producing formations during oil recovery by adding a water soluble polymer of a N-vinyl lactam and a water soluble salt.
U.S. Pat. No. 4,158,521--Anderson et al, issued June 19, 1979, describes treating with a solution of a reaction product of dimethylamine and epichlorohydrin to stabilize clay containing formations in oil and gas producing boreholes after these formations are penetrated.
U.S. Pat. No. 4,366,071--McLaughlin et al, issued Dec. 28, 1982, describes a method of preventing or reducing swelling, migrating or dispersing of clay in an oil producing formation by treating the clay with an organic polycationic polymer dissolved in a carrier to stabilize the clay against dispersion or expansion by water.